The present invention relates generally to wheel alignment systems, and more particularly to laser-based wheel alignment systems.
The axes about which the front wheels of an automobile or truck turn as it travels down the road must be carefully set to minimize tire wear and insure safe and stable handling characteristics. The orientation of these axes is determined by three angles: (1) the toe-in angle, which specifies the angle between the rim of the wheels and a line drawn parallel to the direction in which the car is pointed; (2) the camber angle, which specifies the angle between the rim of the wheels and the vertical; and (3) the caster angle, which specifies the angle between the vertical and the axis about which the individual wheels turn when changing direction. These angles are typically specified individually for each wheel and for each model and make of vehicle, and must be periodically tested and reset as the vehicle and tires age to insure continued economic and safe vehicle performance.
The measurement of these angles has represented a growing challenge to the shops and service stations responsible for alignment service. While simple side-slip gauges were successfully used in the past to check and set toe-in, the readings obtained with such gauges depend on the type of tire installed on the vehicle. In particular, side-slip gauges appear to give widely diverging and erroneous readings for radial tires.
Further, while presently available mechanical alignment machines are capable of measuring the toe-in, camber, and caster angles, the special ramps, gauges, and electronic hardware and software required for operation are beyond the means of many service stations who wish to perform this work.